Vehicle power seat adjuster with self-aligning drive nut

Abstract

A power seat adjuster includes a rotatable drive shaft with first and second axial ends and an intermediate arcuate portion connecting the first and second axial ends. The first and second axial ends are respectively axially connected to a drive motor gear assembly and to a driven lead screw. A horizontal drive block threadingly engaging the lead screw is rotatably and vertically translatingly mounted in an aperture in a lower track for self-alignment of the drive block with respect to the lead screw. A housing rotatably receives the axial connection between one end of the drive shaft and the lead screw. The drive nut is rotatably and translatingly mounted in a bracket fixed to an upper track for self-alignment of the drive shaft with the lead screw. A drive block engages the lead screw and is mounted for rotation and translation in a link. The upper and lower tracks have a guide section and an abutment section which collapse together in a self-cinching action under force loading to resist separation of the upper and lower tracks.

What is claimed is: 
     
       1. A power seat adjuster comprising: a lower track;   an upper track movably mounted on the lower track;   a lead screw;   drive means coupled to the lead screw for rotating the lead screw;   a drive block having a threaded bore extending therethrough threadingly receiving the lead screw; and   co-acting means, formed on the drive block and the lower track, for axially fixedly mounting the drive block to the lower track and for allowing the drive block to move in a rotational movement about an axis vertically transverse to the bore and a vertical translating movement with respect to the lower track.   
     
     
       2. The power seat adjuster of claim 1 wherein the co-acting means comprises: an aperture formed in a lower track, a boss formed on the drive block and mountable in the aperture in the lower track.   
     
     
       3. The power seat adjuster of claim 2 wherein the aperture and the boss each have a circular cross section, with a diameter of the aperture being slightly larger than an outer diameter of the boss. 
     
     
       4. The power seat adjuster of claim 2 wherein: the upper track is spaced a predetermined distance from an upper surface of the drive block, the predetermined distance being less than a length of extension of the boss on the drive block through the aperture in the lower track to retain the drive block in the aperture in the lower track.   
     
     
       5. The power seat adjuster of claim 1 wherein the lead screw is disposed between the upper and lower tracks. 
     
     
       6. The power seat adjuster of claim 1 wherein a recess is formed in an upper surface of the drive block. 
     
     
       7. The power seat adjuster of claim 1 wherein the drive block is formed of plastic. 
     
     
       8. A power seat adjuster comprising: a lower track, an aperture formed in the lower track;   an upper track movably mounted on the lower track;   a lead screw disposed between the upper track and the lower track;   drive means coupled to the lead screw for rotating the lead screw;   a drive block formed of a plastic material and having a threaded bore extending therethrough threadingly receiving the lead screw and a cylindrical boss extending outward therefrom;   the aperture and the cylindrical boss each having a circular cross section, with a diameter of the aperture being larger than an outer diameter of the cylindrical boss to provide rotational movement of the drive block about an axis transverse to the bore in the drive block and translating movement of the drive block along the axis with respect to the lower track; and   the upper track being spaced a predetermined distance from an upper surface of the drive block, the predetermined distance being less than a length of extension of the cylindrical boss on the drive block through the aperture in the lower track to retain the drive block in the aperture in the lower track.